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commitb1ac62a7acupstream. Open-coding a timeout loop invariably leads to errors with handling the timeout properly in one corner case or another. In the case of cqhci we might report "CQE stuck on" even if it wasn't stuck on. You'd just need this sequence of events to happen in cqhci_off(): 1. Call ktime_get(). 2. Something happens to interrupt the CPU for > 100 us (context switch or interrupt). 3. Check time and; set "timed_out" to true since > 100 us. 4. Read CQHCI_CTL. 5. Both "reg & CQHCI_HALT" and "timed_out" are true, so break. 6. Since "timed_out" is true, falsely print the error message. Rather than fixing the polling loop, use readx_poll_timeout() like many people do. This has been time tested to handle the corner cases. Fixes:a4080225f5("mmc: cqhci: support for command queue enabled host") Signed-off-by: Douglas Anderson <dianders@chromium.org> Acked-by: Adrian Hunter <adrian.hunter@intel.com> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20200413162717.1.Idece266f5c8793193b57a1ddb1066d030c6af8e0@changeid Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.